The present invention relates to a semiconductor module for connecting to a transformer winding, and a transformer arrangement that includes a primary winding and a secondary winding comprising a downstream output rectifier arrangement.
Although the present invention is described below essentially with reference to resistance welding systems, it is not limited to an application of this type.
In the case of known transformer arrangements, in particular welding transformer arrangements for resistance welding systems that must provide a relatively high power output, there is a need to adequately cool the electrical components of the secondary/output circuit in particular. It is known, for example, to use reshaped copper pipes as the secondary winding, and to conduct a cooling fluid or a cooling medium through the copper pipe during operation in order to adequately cool the winding. In order to improve the weak mechanical strength of this design, the copper pipes are typically welded to carrier components, e.g., the surfaces, in order to connect the winding. However, heat is added to the material in the welding process, which negatively affects the mechanical properties of the material and may also cause areas to oxidize; these areas must then be cleaned, which is a time-consuming process.
Adequate cooling is also required in the region of the output rectifier due to the relatively high power loss at the rectifier diodes. Known solutions, according to which the rectifier diodes are cooled using cooling bodies, have the disadvantage that the heat dissipation and, therefore, the power output of the transformer arrangement is indirectly limited by the relatively small cooling surfaces. As an improvement, it is proposed in DE 103 34 354 A1 to provide a liquid cooler for power semiconductors, in the case of which two mutually electrically insulated contact members—between which the power semiconductor element is situated—include a groove on their inner surfaces which face the semiconductor component; the groove is open toward the power semiconductor element and is used as the cooling duct. In this solution, the power semiconductor is in direct contact with the cooling medium, which may result in corrosion taking place, and which results in the need for additional sealing. In addition, punctiform areas where a great deal more heat forms (“hot spots”) are difficult to cool if they are located outside of the direct contact area between the semiconductor and the cooling medium.
The conventional placement and orientation of the rectifier diode plane in the main direction of flow also make cooling difficult due to the poor access, and they result in a relatively expensive design, since expensive flexible connectors, such as laminated strips, are required.